Means for working ores by the cyanid process.



No. 701,239. Patented May 27, I902.

. F. D. WOOD.

MEANS FOR WORKING ORES BY THE CYANID PROCESS.

(Application filed Aug. 13, 1901.)

(No Model.)

UNITED STATES AT E T FFICE.

FRANK 1n. wooD, or sAN FRANCISCO, oALIroRNIA.

MEANS FOR )NORKING ORES BY THE CYANID PROCESS.

SPECIFICATION forming part of Letters Patent No. 701,239, dated May 2'7, 1902.

Application filed August 1901- Serial No.71,918. (No model.)

To all whom it may concern:

Be it known that I, FRANK D.WooD, a citizen of the United States, residing in the city and county of San Francisco, State of California, have invented an Improvement in Means for Working Ores by the Cyanid Process 5 andlhereby declare the following to be a full, clear, and exact description of the same.

My invention relates to an improved apparatus for the extraction of precious metals from their ores, and is particularly intended for use in the treatment of such ores in the presence of cyanid solutions.

The object of my invention is to provide a means for expediting the ordinarily slow process of lixiviation.

It consists, essentially, of a trough or containing-tank, through which an endless conveyer is adapted to travel, said conveyer being transversely concaved and in which concavity the ore is held, a series of rollers within said trough and over which the conveyer travels in undulatory movement, whereby the solution is given free access to all particles of the ore carried on the conveyer, and means for subjecting the ore to the oxidizing action of the air as it is passed from one conveyer to another.

It also comprises details which will be more fully set forth hereinafter;

Having reference to the accompanying drawings, Figure 1 is a side elevation of the apparatus. Fig. 2 is a top plan view. Fig. 3 is a longitudinal section through one of the tanks. Fig. 4 is an enlarged cross-section on the line a: a; of Fig. 3.

A represents a trough or tank of any desired size or material, which is adapted to contain a solution of cyanid or othersuitable solvent.

2 represents rollers supported upon arms 12 at either end of said tank, over which an endless conveyer or belt 3 is adapted to travelin such manner that a portion of said belt passes continuously through the solution in said tank and emerging therefrom is returned beneath the tank. This belt is made of suitable fabric, as canvas, secured to chains which pass over sprockets 2 upon the supportingrollers.

The rollers 2 are placedat different elevations above and beyond the tank, so that the conveyer at the rear of the machine is higher than at the head, for reasonsthat will be seen later. In practice the tanks maybe, for example, ten feet in length, and the projection of the carriers may be four feet beyond either end of the-tank.

In the bottom of thetrough are a series of rollers 4, over which the belt passes in undulatory movement, as shown.

Therollers 2 and 4 are concaved, so that in addition to the longitudinal sagging of the belt between the rollers the belt is also given a concaved form transversely. It is by reason ofrthis transverse concavity that the ma terial is retained upon the belt. By means of aworm or other suitable gearing 5 motion is imparted to the belt. This movement is usually very slow, so as to allow a suflicient time for the process of lixiviation. As thus described, the trough, conveyer, rollers, &c., represent one element of my machine.

The pulp or finely-comminuted material is fedonto the more nearly horizontal portion .3 of the belt by suitable means, as the worm carrier 6. The feed-supply may be regulated by arsuitable gate or slide 7. It is desirable that the material shall not extend above the edges of the belt, but shall lie thereon, as in a trough. The depth of the material on the center of the belt may vary from one to ten inches or more, depending on the size of the machine,"rapidity of operation, leaching solution, &c. The belt is supported and kept in properly-distended position by means of the transverse rods 11, secured to the lateral chains. As the'belt moves forward the pulp is slowly passed through the lixiviating solution. The percolation of the latter through the mass is assisted by reason of the rollers at, which sustain the belt at intervals, so that the latter is alternately given a convex and concave form longitudinally. This I convexing of the belt at the points of support causes the particles of material'to be more widely separated, as shown at 8, and the porosity of the mass to be greatly increased, whereupon the solution has access to all parts of the latter. As the belt leaves the trough it travels in an extended upwardly-inclined direction, and the pulp is finally discharged, as at 9, upon a second conveyer 3 and the same process repeated. The slow movement of the pulp upon the portion 10 of the belt allows the solution remaining in the pulp to drain backward into the tank and also allows the air gradually to penetrate the mass and assist in the oxidation of the particles. However, this oxidation, which is an essential part of the lixiviating process, is mainly accomplished when the pulp falls in a disintegrated mass from one conveyer upon the other, whereupon the air has access to all the particles. This breaking up of the mass and exposure to the atmosphere is of very great importance. The pulp is then carried forward over succeeding conveyers until the process of lixiviation is complete. The peculiar construction of the tanks, with their high rear conveyer-supports and low front conveyer portions, causes, further, by the dropping of the particles from one to the other a thorough commingling of the pulp, and the same is passed through the successive solutions without any agitation in the latter. As a consequence the presence of slimes in suspension is less apparent than in ordinary processes, and the subsequent operation of precipitation is accordingly assisted. It is customary and preferable to arrange these tanks in series, so that the said process goes on progressively, continuously, and automatically from the time the ore enters the machine till it is discharged as waste, as at 13. Each conveyer is connected with and driven by the other through the chain-gearing 14, and all may be operated in unison by the worm 5.

Extending beneath the line of tanks is a trough 15, in which any particles falling from the conveyers are caught as the latter pass beneath the tanks on their return.

The number of the tanks and the rate of travel of the conveyers depend on conditions, one class of ore taking often less time than another.

While only three tanks are shown herewith, it is desired to have generally six or more of these tanks in line. These tanks are filled with solutions of varying strengths, it being customary to have the tank into which the ore is first delivered contain the strongest solution, the solutions in the succeeding tanks gradually reducing in strength and the last two tanks containing water alone, in which the pulp is finally washed. As the liquid in these latter tanks becomes more charged with cyanid it may be used as a solvent also. These tanks may, furthermore, be arranged in one or more series, as in Fig. 2, according to the desired capacity of the plant. Having determined on asuitable number of tanks, the speed of the conveyers can be regulated according to the time necessary for proper lixiviation. considerably less than in the ordinary processes, as where the pulp is treated by causing the solution to percolate through it or by working with agitators. The reasons for this are, to reiterate, the manner of travel of the conveyers over the concaved rollers 2 and the breaking up and oxidation of the pulp as it falls from one conveyer upon the other.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. An apparatus for working ores consisting of a plurality of tanks arranged in line, a conveyer passing through each of said tanks and returning thereunder, said conveyer elevated at the rear of the machine more than -at the front, and the rear end of one of the conveyers discharging upon the front end of the other conveyer, and means whereby the conveyers may be driven in unison.

2. An apparatus for working ores comprising a plurality of tanks arranged in line, each of said tanks having a conveyer passingthrough and returning beneath the tank, means for driving the conveyers in unison, and concaved rollers within the tank and upon which the conveyers travel whereby the latter are given an undulatory movement while passing through the tank.

3. In an apparatus for treating ores, a containingtank, an endless transversely-concaved belt conveyer upon which the ore is carried. through the solution in said tank, and means by which an undulatory movement is given to said conveyer.

4. In an apparatus for treating ores, a con taining-tank, an endless-belt conveyer passing through and returning beneath said tank, means supporting one end of the conveyer at a higher elevation than the opposite end, and rollers within the tank over which the conveyer passeswhereby the latter is given an undulatory movement.

It has been found that this time is 5. In an apparatus for treating ores, a containing-tank, an endless-belt conveyer passing through and returning beneath said tank, concaved rollers upon which said conveyer is sustained and rods supporting the edges of said conveyer whereby the latter is kept disless belt passing through and returning beneath each of said tanks, and upon which the ore is carried, each of said belts discharging its lead upon the belt of the next succeeding tank, means for driving said belts in unison, means by which said belts are kept transversely distended and rollers disposed at intervals in said troughs and over which the belts pass, whereby the latter are given an undulatory movement. 10

In witness whereof I have hereunto set my hand.

FRANK D. WOOD. Witnesses:

S. H. N OURSE, JEssIE O. BRODIE. 

